This invention relates to an ice cube-making machine that is quiet at the location where ice is dispensed.
Ice cube-making machines generally comprise an evaporator, a water supply and a refrigerant/warm gas circuit that includes a condenser and a compressor. The evaporator is connected to the water supply and to a circuit that includes the condenser and the compressor. Valves and other controls control the evaporator to operate cyclically in a freeze mode and a harvest mode. During the freeze mode, the water supply provides water to the evaporator and the circuit supplies refrigerant to the evaporator to cool the water and form ice cubes. During the harvest mode, the circuit converts the refrigerant to warm gas that is supplied to the evaporator, thereby warming the evaporator and causing the ice cubes to loosen and fall from the evaporator into an ice bin or hopper.
When installed in a location, such as a restaurant, where a small footprint is needed, ice making machines have been separated into two separate packages or assemblies. One of the packages contains the evaporator and the ice bin and is located within the restaurant. The other package contains the compressor and condenser, which are rather noisy. This package is located remotely from the evaporator, for example, outside the restaurant on the roof. The evaporator package is relatively quiet as the condenser and compressor are remotely located.
This two package ice cube-making machine has some drawbacks. It is limited to a maximum height distance of about 35 feet between the two packages because of refrigerant circuit routing constraints. Additionally, the compressor/condenser package weighs in excess of about 250 pounds and requires a crane for installation. Furthermore, service calls require the mechanic to inspect and repair the compressor/condenser package in the open elements, since it is typically located on the roof of a building. Due to inclement weather, it would be highly desirable to be able to work on the compressor in doors, since it is only the condenser that requires venting to the atmosphere.
During harvest mode, the condenser is bypassed so that refrigerant is supplied from the compressor in vapor phase to the evaporator. When the compressor is located a distance from the evaporator, the refrigerant tends to partially change to liquid phase as it traverses the distance, thereby affecting the efficiency warming or defrosting the evaporator. One prior art solution to this problem uses a heater to heat the vapor supply line. Another prior art solution locates a receiver in the same package as the evaporator and uses the vapor ullage of the receiver to supply vapor to the evaporator. Both of these solutions increase the size of the package and, hence, its footprint in a commercial establishment.
Thus, there is a need for a quiet ice cube-making machine that has a larger height distance between the evaporator and the condenser and a lighter weight for installation without the need for a crane.
There is also a need for an efficient way of providing vapor to an evaporator during harvest mode.
The ice cube-making machine of the present invention satisfies the first need with a three package system. The condenser, compressor and evaporator are located in separate ones of the packages, thereby reducing the weight per package and eliminating the need for a crane during installation. The compressor package can be located up to 35 feet in height from the evaporator package. For example, the evaporator package can be located in a restaurant room where the ice cubes are dispensed and the compressor package can be located in a separate room on another floor of the building, such as a utility room. This allows for service thereof to be made indoors, rather than outdoors as required by prior two package systems. The condenser package can be located up to 35 feet in height from the compressor package. For example, the condenser package can be located on the roof of the multistory building.
The evaporator package has a support structure that supports the evaporator. The compressor package has a support structure that supports the compressor. The condenser package has a support structure that supports the condenser.
The present invention satisfies the need for providing vapor to the evaporator during harvest mode by increasing the pressure and temperature of the refrigerant in the evaporator. This is accomplished by connecting a pressure regulator in circuit with the return line between the evaporator and the compressor. The pressure regulator limits flow, which increases pressure and temperature of the refrigerant in the evaporator. To achieve a small footprint of the evaporator package, the pressure regulator can be located in the compressor package.